#include <stdio.h>
#include <string.h> 
#include <stdlib.h>
struct node
{
    int data;
    struct node *next;
};
typedef struct node *stack;
stack initStack()
{
    stack s=(stack)malloc(sizeof(struct node));
    s->next=NULL;
    return s;
}
int isEmpty(stack s)
{
    return s->next==NULL;
}
void push(stack s,int x)
{
    stack p=(stack)malloc(sizeof(struct node));
    p->data=x;
    p->next=s->next;
    s->next=p;
}
void pop(stack s,int *x)
{
    stack p=s->next;
    if(isEmpty(s))
    {
        printf("Stack is empty!\n");
        return;
    }
    s->next=p->next;
    *x=p->data;
    free(p);
}
int getTop(stack s)
{
    return s->next->data;
}

int Palindrome(char str[],int n)
{
    char *p=str;
    stack s=initStack();
    for(; p<str+n/2; p++)
        push(s,*p);
    if(n%2)    p++;
    while(*p!='\0')
    {
        int x;
        pop(s,&x);
        if(x!=*p)
            return 0;
        p++;
    }
    return 1;
}
int main()
{
    int len;
    char str[100];
    gets(str);
    len=strlen(str);
    if(Palindrome(str,len)){
        printf("yes");
    }else{
    printf("no");
    }
    return 0;
}
